The present invention relates to a lid latch device adapted to be used for a back lid of a camera, more specifically, it relates to a device for releasably latchlag a back lid of a camera that covers a recessed portion which is formed on the back surface of the camera and provides a film chamber for holding a film cartridge inserted into the camera and a take up spool used to wind the film forward and store the film already exposed.
Conventionally, there is provided a recessed portion for holding a film inserted into a camera, the recessed portion being covered by a back lid which can be swung open. The back lid is attached to a hinged portion at one end and has an engaging portion at the other end. The engaging portion engages another engaging portion that is formed on the side of the recessed portion. When the back lid is closed the two engaging portions are latched together, resulting in the back lid and recessed portion forming a light-tight enclosure.
When an open button which is attached to either the back lid or the recessed portion is slid, the latch is released and the engaging portions of the back lid and the back surface of the camera are disengaged from each other. Accordingly, the back lid is released from the closed position, and the recessed portion can be accessed to load or remove the film.
Recently, there is provided a camera which is equipped with an auto-loading function. In the camera with the auto-loading function, when the open button is first slid, the back lid is released from the closed position, and a film chamber provided in the recessed portion is accessible. Thereafter, a film cartridge from which the leading end portion of the film is drawn out by a predetermined amount is placed in the film chamber and the leading end portion of the film is positioned on a spool shaft. The back lid is then latched closed to cover the recessed portion. When both of the engaging portions are latched together, the film loading operation is automatically initiated. That is, the spool shaft automatically starts rotating, engaging the leading end portion of the film with the spool shaft. The film is automatically wound up around the spool shaft and drawn out from the cartridge until a condition occurs where it is possible to take a photograph is established.
In the conventional camera with the auto-loading function, when the open button is slid to an open position thereby opening the back lid, the open button is held in this open position. When the back lid is latched closed, the open button is released from the open position and returned to the closed position. Further, there is provided a detection device by which the closed position of the open button is detected.
Accordingly in the conventional camera, when the open button is returned to the closed position, this action is detected by the detection device, and the auto-loading operation of the film is started.
However in the conventional camera with the auto-loading function, when an unexpected force or shock is applied to the camera while the back lid is opened during a film loading operation, the open button may be accidentally disengaged from the open position due to the impact force and slide to the closed position. If this happens, the detection device will detect the closed position of the open button even though the back lid is opened and thereby start the auto-loading operation of the film. This will result in the film being wound while the recessed portion is not light-tight, thereby exposing the image recording portion of the film to light, rendering some frames of the image recording portion unusable.
Further the leading edge of the film may be wound before the film cartridge had been properly inserted into the film chamber. This may result in improper winding of the film which could lead to the film being bent or otherwise damaged. This would require corrective action from the photographer, which is both bothersome and time-consuming.